(a) Field of the Invention
The present invention relates to a device and method for compensating for phase distortions in a base station of an OFDMA (orthogonal frequency division multiple access) based cellular system. More specifically, the present invention relates to a device and method for compensating for phase distortions in a base station of an OFDMA-based cellular system, in which the device and method allow multiple access in the uplink of the OFDMA-based cellular system.
(b) Description of the Related Art
Following developments in next-generation mobile communication systems, many methods have been proposed for providing various services including high-quality and high-speed multimedia services. However, the deterioration in performance caused by multipath fading channels in mobile communication environments has become serious impediments to realizing such services.
Therefore, many techniques for overcoming the deterioration in performance caused by multipath fading have been developed and used. A drawback of these techniques, however, is that although they minimize such performance deterioration, the techniques require the design of a complex receiver.
The OFDMA method has been suggested for easily solving the problem of deterioration in performance caused by multipath fading by using a simple demodulator.
In the OFDMA method, a total of N subcarriers are divided into groups in a single OFDM symbol and in such a manner that the subcarriers are not repeated, and one of the divided groups (or subchannels) is allocated to each mobile station user.
In the OFDMA method, each mobile station loads data to a subcarrier in the group and transmits the data during a predetermined time frame in the reverse link case. Since the subcarriers included in the subchannel allocated to users who stay in a single cell belong to a single OFDMA symbol, it is necessary for a base station receiver to perform synchronization between each of the subchannels received from the mobile station. That is, in order to perform accurate demodulation, it is necessary that the base station receiver perform the same FFT (fast Fourier transform) at the same symbol timing.
Hence, OFDMA flexibly processes various services for the multitude of requests made by users, but results in the deterioration of performance compared to other multi-user access methods when the multiple users are not synchronized in the uplink.